California took some of its most aggressive steps yet to fight global warming as lawmakers passed a flurry of new climate bills late Wednesday, including a record $54 billion in climate spending, a measure to prevent the state’s last nuclear power plant from closing, sharp new restrictions on oil and gas drilling and a mandate that California stop adding carbon dioxide to the atmosphere by 2045.

The bills, passed around midnight at the end of a frenzied two-year legislative session in Sacramento, marked a victory for Gov. Gavin Newsom, a Democrat who has sought to portray himself as a climate leader as he has raised his national profile and begun drawing speculation about a possible White House run.

Mr. Newsom upended the legislative session in mid-August when